This invention generally relates to golf balls and, more particularly, to a selectively weighted golf ball.
Conventional golf balls have been designed to provide particular playing characteristics. These characteristics typically include initial velocity, compression, and spin of the golf ball, and can be optimized for various types of players. For example, certain players prefer a ball that has a high spin rate in order to control the flight of the ball and to stop the golf ball on the green. This type of ball, however, does not usually provide maximum distance. Other players prefer a ball that has a low spin rate and high resiliency to maximize distance.
Early solid golf balls were generally comprised of a hard core and a hard cover. Generally, if the golf ball has a soft core and a hard cover, it has a low spin rate. If the golf ball has a hard core and a hard cover, it exhibits very high resiliency for distance, but a xe2x80x9chardxe2x80x9d feel and is difficult to control on the greens. Additionally, if the golf ball has a hard core and a soft cover, it will have a high rate of spin. More recently developed solid balls are comprised of a core, at least one intermediate layer, and a cover. The intermediate layers improve the playing characteristics of solid balls and can be composed of thermoset or thermoplastic materials.
Typically, solid golf ball cores are spherical and solid. In an effort to improve the spin rate of balls, the weight distribution in the golf ball has been varied by concentrating the weight either in the spherical inner cores or in the mantle(s) near the surface of the ball. It is desired, therefore, to provide a golf ball with symmetrical, non-spherical weight distribution that provides unique spin rate characteristics.
Several patents are directed to inner cores that have been modified with non-spherical features such as bores or projections.
U.S. Pat. No. 720,852 issued to Smith discloses an internal core with small, solid protuberances projecting therefrom. The core is encased in a rubber layer having small, solid protuberances projecting therefrom. A silk layer is wound thereto, and then the ball is encased in an outer covering. The non-spherical core protuberances anchor the rubber and silk layers and increase the resiliency of the ball as a whole, but have no weight distribution function.
U.S. Pat. No. 1,524,171 issued to Chatfield discloses a core with a hollow, spherical center that supports cylindrical, solid lugs. A spherical casing surrounds and abuts the tips of the lugs. The lugs and casing are designed so that the casing compresses the lugs in the finished ball. Fluid or wound rubber bands occupy the space around the lugs, between the spherical center and the casing. The non-spherical lugs promote the accurate location of the center by facilitating uniform and spherical winding of the rubber bands about the center, but have no weight distribution function. An outer shell surrounds the casing.
U.K. Patent Application No. 2,162,072 issued to Slater discloses a golf ball with a non-spherical inner core that includes solid, support members or struts that diverge from a common center. The struts form a generally cubic, tetrahedral, or octahedral shaped core. The struts locate the inner core symmetrically within a mold cavity but perform no weight distribution. An outer core is molded about the inner core, and a cover is molded thereon. The inner and outer cores are formed from identical or similar materials.
U.S. Pat. No. 5,480,143 issued to McMurry discloses a substantially spherical practice ball comprising mutually perpendicular members with a plurality of walls that interconnect the members. The walls increase the drag on the ball so that smaller playing fields can be used.
U.S. Pat. No. 5,836,834 issued to Masutani et al. discloses a two or three piece golf ball comprising a two-layer solid core composed of a low-hardness inner core and a high-hardness outer core joined around the low-hardness inner core. A projection is formed on the inner surface of the high-hardness outer core such that the projection extends along an approximate normal direction, while a depression corresponding to the projection is formed in the outer surface of the low-hardness inner core, and the low-hardness inner core and the high-hardness outer core are joined together such that the projection is inserted into the depression.
Other patents disclose adding perimeter weights to golf balls to increase its moment of inertia. U.S. Pat. No. 5,984,806 discloses a golf ball with visible perimeter weights disposed on a spherical inner cover.
However, these patents do not disclose a golf ball having the configuration as disclosed herein to provide the improved golf balls of the present invention.
The present invention is directed to a golf ball having a core geometry designed to provide improved playing characteristics such as spin rate.
The present invention is also directed to a golf ball having an inner core that comprises a pre-formed selectively weighted insert.
The present invention is further directed to a golf ball comprising a pre-formed selectively weighted inner core insert adapted to have an outer core molded over the inner core. The ball also has a cover around the outer core. In accordance to one aspect of the invention, the pre-formed insert has a high specific gravity center hub and low specific gravity outer elements thereby forming a low moment of inertia, high spin rate ball. In accordance to another aspect of the invention, the preformed insert has high specific gravity outer elements forming a high moment of inertia, low spin rate ball.
In accordance to another aspect of the present invention, the inner core insert comprises outer pockets thereon. These pockets are adapted to receive a portion of the outer core material. When the outer core material has a high specific gravity the ball has high moment of inertia, and when the outer core material has a low specific gravity the ball has a low moment of inertia.